Research On The Aeolian Dunes In The Field Of Qinhuangdao

Qinhuangdao coast is the typical coast of sand blown by wind in China. In the area, wind-induced dunes have been well investigated and studied by many scholars from different angles, but no one can research generally by far. In this paper, the author gives a full description about the wind-induced dunes along the coast of Qinhuangdao, combining with the investigation of inside and outside researchers of coastal dunes and basing on a large number of data derived from field investigation. The sand dunes are distributed mainly in the area of Changli and Funing, where is named "Gold Coast" and is the best place of the wind-induced dunes developing on the shore of Bohai bay. There are fives kinds dunes along the coast from the sea to the land, including coastal foredunes, longshore dune chains, oblique dune chains and sand sheet and so on. The surface of dune grows sand ripples. We make sure the windward slope and leeward slope on the basis of actual survey, finding whether the windward slope or the leeward slope have quite slow foot and steep top. The sediments of dunes are mainly composed of well-sorted medium and find-grain sand, which have a similar grain distribution with beach sand deposits. The grain-size distributions of sand dunes are characterized by slightly nagative-skewness and both bounce movings. The kurtosis of the dune sands are bigger than 3 and very edge. The scatter plot diagrams of the four size parameters of the beach sands and dunes have a definite disciplinarian relatively, but there is difficult to distinguish them. Because the onshore wind and the offshore wind are varitional frequent. Quartz grains in the study area are founded to be mainly subrounded and subangular, and little difference between the properties of the dune sand and the beach sands is noted. The quartz grains from dune sands are dish-shaped concave, upturned plate and subaqua V-shaped depressions on their surface. High-angle tabular cross-bedding and low-angle wedge cross-bedding are generally found on the cross-section of dunes. Reaction surface can be found always because of wind direction and velocity changing. The original sand source for coastal dunes is Luanhe River .The abundant fluvial sediments are transportednorthward and deposited on the beach by the alongshore and waves. Wide and low-angle beach is ideal location for these criteria to be met and the offshore wind blows the well-sorted sand grains off the beach and transports the landward, then builds up to coastal dunes. At present time, the coastal dunes are still actives. The sand dunes move to land with the influence of natural factors and the average velocity is 2-3 m/s in the past several decades. At the same time, the negative influence of beach affects the development of sand dunes at last on account of tour activities. The sliding-sand makes the altitude of sand dunes lower. In the paper, the author discuss many problem about protect and utilize coastal dunes, and has posed suggestion from the long views that protect the natural visage of the sand dunes and the entironments, accelerating the tour continual develement.